The present invention relates to a semiconductor integrated circuit device, and more particularly, to a technique that is effective for use in a for-camera preprocessing LSI (Analog Front End) including a correlated dual sampling (CDS) circuit and a variable gain amplifier such as a programmable gain amplifier (PGA).
For example, Japanese Unexamined Patent Publication No. 2001-189892 (patent document 1) describes an example of a front-end signal processor for digitally providing a clamp offset in processing a signal from an image sensor. As shown in FIG. 3 of patent document 1, a digital brightness signal subjected to compensation for black level variation is converted by a DAC into an analog signal, which is integrated by a capacitor through a gate, so that a feedback voltage for compensating for a black level is stored.
[Patent document 1] Japanese Unexamined Patent Publication No. 2001-189892